Methods and apparatus for mounting a motor controller on a stator assembly

ABSTRACT

A method for fabricating a motor is described that includes attaching a circuit board of a motor control assembly to a first side of a mounting adapter, and attaching a second side of the mounting adapter to a stator assembly.

BACKGROUND OF THE INVENTION

The field of the disclosure relates generally to electric machines, andmore specifically, to methods and apparatus for mounting a motorcontroller on a stator assembly.

As described herein, at least one existing motor control assembly issituated in an aluminum housing which is subsequently attached to amotor chassis, adjacent an end shield. In another described motor, a“mid-shield” is installed into the motor chassis, which supports themotor bearing, and allows for the components of the motor controlassembly to extend into the motor chassis, eliminating one end shieldfrom such motor assemblies.

Solid end shields obstruct airflow. As a consequence of using a solidend shield, electronics in the motor control assembly do not getadequately cooled. In addition, the windings of the motor are notadequately cooled when an end shield is incorporated between thewindings and the motor controller. Reliability and efficiency of themotor may suffer.

Other attempts at mounting a control assembly on stator assemblies havebeen made. In one process, posts are molded around the perimeter of aplastic stator end-cap and corresponding mating holes are created in thecircuit board of the motor control assembly to fit with these posts.After the circuit board is seated, the protruding ends of the posts thatextend beyond the board are melted down to hold the board in place. Sucha process is slow, prone to human error and impractical for rework.

In another configuration, snap-in fingers are formed around the plasticstator end-cap. These flexible fingers allow the circuit board of themotor control assembly to snap in and hold it in place. The snap-infingers are part of the end-cap structure and one drawback to such aconfiguration is that the protruding fingers tend to interfere with thestator winding process, and the snap-in fingers may break off fromhandling in the manufacturing process.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a method for fabricating a motor is provided. The methodincludes attaching a circuit board of a motor control assembly to afirst side of a mounting adapter, and attaching a second side of themounting adapter to a stator assembly.

In another aspect, an electric machine is provided that includes astator assembly, a motor control assembly having a circuit board, and amounting adapter having a first side and a second side. The first sideis configured for engagement with the circuit board, and the second sideconfigured for engagement with the stator assembly. The mounting adapteris operable for maintaining a position of the circuit board with respectto the stator assembly.

In still another aspect, a mounting adapter is provided that includes afirst side and a second side. The first side is configured forengagement with a circuit board of a motor control assembly, and thesecond side is configured for engagement with a stator assembly. Themounting adapter is operable for maintaining a position of the circuitboard with respect to the stator assembly.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments further details of which can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an integrated electronically commutatedmotor (ECM) and control circuit assembly.

FIG. 2 is an exploded partial view of an ECM that includes a mid shieldwhich allows a control circuit to fit into the main chassis of the ECM.

FIG. 3 is an illustration of an adapter that attaches a motor controlassembly to a stator assembly.

FIG. 4 is an exploded view of a motor that incorporates the adapter ofFIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

The methods, systems, and apparatus described herein facilitateefficient and economical manufacturing of an electric machine. Althoughdescribed herein as associated with an electric motor, the methods,systems, and apparatus described herein may also be associated with anelectric generator.

Embodiments are directed to an adapter for mounting a motor controlleron a stator assembly offering features for manufacturing application andservice.

Referring to the drawings, and more particularly to FIG. 1, referencecharacter 11 generally designates one known integrated electronicallycommutated motor and control circuit assembly. Motor assembly 11includes a brushless electronically commutated DC motor 13 having astationary assembly 15 including a stator core 17 and a rotatableassembly 19 including a permanent magnet rotor 12 and a shaft 14. A fan(not shown) or other means to be driven such as means for moving airthrough an air handling system engages the shaft 14.

Rotor 12 is mounted on and keyed to the shaft 14 journaled for rotationin conventional bearings 16. The bearings 16 are mounted in bearingsupports 18 integral with a first end member 20 and a second end member22. The end members 20 and 22 are substantially flat and parallel toeach other and may be referred to as end shields. The end members 20 and22 have inner facing sides 24, 25 between which the stationary assembly15 and the rotatable assembly 19 are located. Each end member 20 and 22has an outer side 26, 27 opposite its inner side 24, 25. Additionally,second end member 22 has an aperture 23 for the shaft 14 to pass throughand extend out from the outer side 26.

The rotor 12 comprises a ferromagnetic core 28 and is rotatable withinthe bore of stator 17. In the illustrated embodiment, eight essentiallyidentical magnetic material elements or relatively thin arcuate segments30 of permanent magnet material, each providing a relatively constantflux field, are secured, for example, by adhesive bonding to rotor core28. The segments 30 are magnetized to be polarized radially in relationto the rotor core 28 with adjacent segments 30 being alternatelypolarized as indicated. Alternatively, arcs with multiple north-southpairs may be utilized. Motor having interior permanent magnets, forexample, mounted within the core 28 are also known.

Stationary assembly 15 comprises a plurality of winding stages 32adapted to be electrically energized to generate an electromagneticfield. Stages 32 are coils of wire wound around teeth 34 of thelaminated stator core 17. The winding end turns extend beyond the statorend faces and winding terminal leads 40 are brought out through anaperture 41 in the first end member 20 terminating in a connector 42.While stationary assembly 15 is illustrated for purposes of disclosure,other stationary assemblies of various other constructions havingdifferent shapes and with different number of teeth are known.

Motor assembly 11 further includes a cap 44 which is mounted on the rearportion of the motor assembly 11 to enclose within the cap 44 controlmeans 46 for the motor 13. The cap 44 and the control means maysometimes be referred to collectively as a motor control assembly. Cap44 includes a substantially annular side wall 49. When assembly iscompleted, the control means 46 are positioned adjacent the outer side27 of the first end member 20. The control means 46 includes a pluralityof electronic components 52 and a connector (not shown) mounted on acomponent board 56, such as a printed circuit board. The control means46 is connected to the winding stages 32 by interconnecting connector 42and connector (not shown). The control means 46 applies a voltage to oneor more of the winding stages 32 at a time for commutating the windingstages 32 in a preselected sequence to rotate the rotatable assembly 19about an axis of rotation.

As mentioned herein, the engagement between the first end member and thecap 44, which is sometimes referred to as a housing, substantially formsa chamber for electronic components 52 and component board 56 which doesnot allow for any air flow across the components 52.

To effect this engagement, connecting elements 58 comprising a pluralityof bolts pass through bolt holes 60 in the second end member 22, boltholes 61 in core 17, bolt holes 63 in first end member 20, and boltholes 65 in cap 44. The head 67 of the connecting elements 58 engage thesecond end member 22. The connecting elements 58 are adapted to urge thesecond end member 22 and the cap 44 toward each other thereby supportingthe first end member 20, the stationary assembly 15, and the rotatableassembly 19 therebetween. Additionally, a housing, or chassis, 62 may bepositioned between the first end member 20 and the second end member 22for enclosing and protecting the stationary assembly 15 and therotatable assembly 19.

Attempts have been made to address the airflow issues noted above, andto reduce the number and/or weight of components associated with suchmotors. For example, FIG. 2 is an exploded end view of an embodiment ofanother known motor 100. Motor 100 includes a motor enclosure 102 and amotor control unit 104 configured for attachment to motor enclosure 102.A chassis 105 of motor control unit 104 serves as an end shield 106 formotor 100. Motor enclosure 102 also includes a slot 108 which engages aheat sink 109 formed in chassis 105 as further described below. Whilemotor control unit 104 includes chassis 105, motor 100 is configuredsuch that motor enclosure 102 provides substantially all of theenclosure for motor control unit 104. Within motor enclosure 102 arewindings 110 of motor 100 and a mid shield 112 configured for placementbetween windings 110 and motor control unit 104.

The placement and configuration of mid shield 112 allows motor controlunit 104 of motor 100 to be removed and replaced without disruption ordisplacement of a motor winding assembly 124 which includes windings 110of motor 100. As illustrated, motor enclosure 102 is configured to forma part of the enclosure for motor control unit 104, along with endshield 106, allowing for a one-piece enclosure configuration. Mid shield112 is also configured to meet any airflow, voltage clearances andassembly height limitations imposed on motor 100.

In one embodiment, as illustrated, mid shield 112 fits precisely withrespect to a centerline 125 of motor 100 and further aligns with twobolts 126 that pass through end shield 106 of motor control unit 104 toclamp and secure mid shield 112 and motor control unit 104 within motorenclosure 102. Mid shield 112 also contributes to a lower material costfor motor 100, because with mid shield 112, motor enclosure 102 isutilized as a part of the containment enclosure for portions of motorcontrol unit 104 as shown in FIG. 2, decreasing the size and number ofcomponents of motor 100 as compared to motor 11 (shown in FIG. 1).Additionally, such a configuration allows for a placement of a powerconnector 128 that is flush with chassis 102.

Utilization of mid shield 112 allows motor control unit 104 to beremoved from enclosure 102 without disturbing the rest of the motorassembly, for example, windings 110. The non-disturbance is obtained byusing mid shield 112 to secure a bearing that engages a motor shaft(neither shown in FIG. 1) of motor 100. Therefore, enclosure 102 isadditionally configured to provide any required clearances for theelectrical components (e.g., motor control unit 104) of motor 100 toallow disengagement of motor control unit 104 from motor 100. Insummary, motor 100 is an improvement over motor 11 in that there is noseparate end member 20, and the configuration of the mid shield 112allows for airflow that might be generated by motor operation to be ofat least some use in cooling the electronic components that are mountedand housed within motor control unit 104.

FIG. 3 is an illustration of a motor control mounting adapter 200. Asshown in FIG. 4, adapter 200 is configured to attach to a statorassembly 300 and engage a motor control assembly 400, specifically, acircuit board 402 of the motor control assembly 400. Once the adapter200 attaches the motor control assembly 400 to the stator assembly 300the combination may be inserted into a motor chassis 410. Alternatively,the stator assembly 300 may already be placed within chassis 410, andthe adapter 200 is then inserted into the motor chassis 410 to engagethe stator assembly 300.

Referring back to FIG. 3, the main architecture of the adapter 200consists of a ring 202 which operates as a base for snap latches 210,212, 214, 216, 218 about the perimeter of the ring 202. In use, acircuit board, such as circuit board 402, is pressed onto a top side 220of the adapter 200. As the circuit board is pressed down, the snaplatches 210, 212, 214, 216, 218 that extend from the top side 220 ofring 202 flex outward to allow the circuit board to be properlypositioned with respect to the adapter 200. When the circuit board isseated, the snap latches 210, 212, 214, 216, 218 flex back, with thetangs 230 molded thereon operating to retain the circuit board in place.Similarly, stator engaging latches 240, 242, 244, 246, and 248 extendingfrom a bottom side 250 of adapter 200 operate to engage correspondingopenings in a stator assembly 300 as can be discerned from FIG. 4.

The snap latches 210, 212, 214, 216, 218 on the top side 220 of theadapter ring 200 operate to secure a circuit board, and therefore thecomponents mounted thereon, in place while providing a configurationthat allows for relatively easy installation and removal of the motorcontrol assembly 400.

The stator engaging latches 240, 242, 244, 246, and 248 that extend fromthe bottom side 250 of the ring 202 allow for latching of the ring 202,and therefore the motor control assembly 400, to stator assembly 300thereby saving a stator end-cap 302 from having dedicated features forboard mounting and bringing no impact to the existing manufacturingprocess. Instead, end-caps 302 may be configured as simple plasticinsulators on each end of the stator assembly 300.

As discerned from FIGS. 3 and 4, placement of the snap latches 210, 212,214, 216, 218 and the stator engaging latches 240, 242, 244, 246, and248 configure the adapter ring 200 with polarizing and keying featuresto ensure correct mating between the various components. One embodimentof adapter 200 incorporates a wire barrier 260 and a tie wrap post 270for tying and constraining magnet wires. Various embodiments of adapter200 incorporate a mounting guide 280, which is a straightened areawithin the ring 202 as well as reinforcing structures 290 placed aboutthe ring 202. A polarizing and keying structure 290 help an externalconnector to mate with the connector on the control assembly 400.

The adapter 200 described herein enables the motor control assembly 400to be mounted on the stator assembly 300, acting as a bonding devicebetween the motor control assembly 400 and the stator assembly 300 asseen in FIG. 4. On the top side 220 of the adapter 200, snap latches210, 212, 214, 216, 218 are deployed to allow the circuit board 402 tobe secured into the adapter 200. On the bottom side 250 of the adapter200 stator engaging latches 240, 242, 244, 246, and 248 are deployed tohook the adapter 200 onto a stator assembly 300 or a stator end-cap 302formed as a part of stator assembly 300.

With the motor control assembly 400 mounted on the stator assembly 300,a shaft of the motor may extend through a hole 404 formed in the circuitboard 402 to an end shield, thus eliminating a mid-shield. In regard tothermal improvement, a solid end shield obstructs airflow. By mountingthe motor control assembly 400 on the stator assembly 300 and creatingopenings in both end shields, a air stream blows from end to end throughthe motor as it runs. Both the electronic components and motor windingsare cooled effectively.

The motor control assembly 400 can be pressed into the adapter 200without over-stressing the snap latches 210, 212, 214, 216, 218 whichoperate to hold the motor control assembly 400 in a tight and securemanner. The adapter 200 and motor control assembly 400 combination canbe pressed onto the stator end-cap 302 without over-stressing the statorengaging latches 240, 242, 244, 246, and 248. The stator engaginglatches 240, 242, 244, 246, and 248 allow adapter 200 to retain themotor control assembly 400 in position with respect to the statorassembly 300 in a tight and secure manner.

This written description uses examples to disclose various embodiments,which include the best mode, to enable any person skilled in the art topractice those embodiments, including making and using any devices orsystems and performing any incorporated methods. The patentable scope isdefined by the claims, and may include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral languages of the claims.

What is claimed is:
 1. An electric machine comprising: a stator assembly comprising an insulating end-cap; a motor control assembly comprising a circuit board; and a ring shaped mounting adapter comprising a diameter slightly less than an inside perimeter of a chassis for said motor, a first side, and a second side, said first side configured for engagement with said circuit board, said second side configured for engagement with said insulating end-cap of said stator assembly, said mounting adapter operable for maintaining a position of said circuit board with respect to said stator assembly.
 2. The electric machine according to claim 1 wherein said mounting adapter comprises a plurality of flexible snap latches that extend from said first side of said mounting adapter, said plurality of flexible snap latches operable for retaining said circuit board in position with respect to said mounting adapter.
 3. The electric machine according to claim 2 wherein said flexible snap latches are spaced about a perimeter of said mounting adapter.
 4. The electric machine according to claim 1 wherein said mounting adapter comprises a plurality of flexible stator engaging latches that extend from said second side of said mounting adapter, said plurality of stator engaging latches operable for engaging said insulating end-cap.
 5. The electric machine according to claim 4 wherein said stator engaging latches are spaced about a perimeter of said mounting adapter.
 6. The electric machine according to claim 1 wherein said mounting adapter comprises at least one of: a polarizing and keying structure configured to ensure correct mating between an external connector and a connector on the motor control assembly; at least one wire barrier for constraining motor wiring; at least one tie wrap post for tying wiring of said motor; and at least one mounting guide for aligning said mounting adapter with one or more of said insulating end-cap, said motor control assembly, and a chassis for said motor.
 7. The electric machine according to claim 1 wherein said circuit board comprises a hole therethrough, said hole substantially centered with a longitudinal axis of said electric machine and operable for placing a shaft of said motor therethrough for engagement with an end shield for said motor.
 8. A mounting adapter comprising a first side, a second side, a plurality of flexible snap latches that extend from said first side, and a plurality of flexible stator engaging latches that extend from said second side, said plurality of flexible snap latches configured for engagement with a circuit board of a motor control assembly and operable for retaining the circuit board in position with respect to said mounting adapter, said plurality of flexible stator engaging latches configured for engagement with an insulating end cap of a stator assembly, said mounting adapter operable for maintaining a position of the circuit board with respect to the insulating end cap.
 9. The mounting adapter according to claim 8 further comprising at least one of: a polarizing and keying structure configured to ensure correct mating between an external connector and a connector on the motor control assembly; at least one wire barrier for constraining motor wiring; at least one tie wrap post for tying wiring of a motor; and at least one mounting guide for aligning said mounting adapter with one or more of the insulating end-cap, the motor control assembly, and a chassis for the motor.
 10. The mounting adapter according to claim 8 wherein said mounting adapter comprises a ring shape of a diameter slightly less than an inside perimeter of a chassis for a motor.
 11. The mounting adapter according to claim 10 wherein said flexible snap latches are spaced about a perimeter of said mounting adapter.
 12. The mounting adapter according to claim 10 wherein said stator engaging latches are spaced about a perimeter of said mounting adapter.
 13. A method for fabricating a motor, said method comprising: attaching a circuit board of a motor control assembly to a first side of a ring shaped mounting adapter having a diameter slightly less than an inside perimeter of a motor chassis; and attaching a second side of the mounting adapter to an insulating end-cap coupled to a stator assembly.
 14. The method according to claim 13 further comprising inserting the mounting adapter and motor control assembly combination into a motor chassis for attachment to the stator assembly.
 15. The method according to claim 13 wherein attaching a circuit board of a motor control assembly to a first side of a mounting adapter comprises pressing the circuit board onto the mounting adapter such that the circuit board is engaged by a plurality of flexible snap latches that extend from the mounting adapter, the plurality of flexible snap latches spaced about a perimeter of the mounting adapter.
 16. The method according to claim 15 further comprising retaining the circuit board in position with respect to the mounting adapter through the engagement of tangs on the flexible snap latches with the circuit board.
 17. The method according to claim 13 further comprising configuring the mounting adapter with a polarizing and keying structure configured to ensure correct mating between an external connector and a connector on the motor control assembly.
 18. The method according to claim 13 further comprising configuring the mounting adapter with at least one of: a wire barrier for constraining motor wiring; a tie wrap post for tying motor wiring; and a mounting guide for aligning the mounting adapter with one or more of the insulating end-cap, a motor control assembly and a motor chassis.
 19. The method according to claim 13 further comprising placing a shaft of the motor through a hole in the circuit board for engagement with a motor end shield. 